1. Field of the Invention
The present invention relates to a screw cap of semi-rigid plastic material, or the like, for necks of containers such as bottles, and particularly relates to a closed, tamper-proof hold ring developed integral with the body of the cap and connected by several breakable attachment tabs to the lower edge of the body of the cap. The hold ring is intended to catch below a mating ring or collar located generally at the neck of the container.
2. Description of the Prior Art
Many known tamper-proof systems for screw caps of plastic material, or the like, generally comprise a tamper-proof hold ring of the "catch" type. Upon placing the cap on the neck of the container, the hold ring "jumps over" the thread of the neck and places itself behind the mating ring or collar at the neck. These catch-type tamper-proof hold rings are located substantially in the downward extension of the lower edge of the cap body. Their main drawback is that the manufacture of a cap having such a hold ring requires a complicated so-called "drawer" mold to permit removal of the cap together with its tamper-proof ring from the mold because the tamper-proof ring forms an undercut portion with respect to the side wall of the cap.
Another known tamper-proof hold ring cooperates with a mating ring or collar at the neck of the container, not by catching on the mating ring or collar, but by shrinkage of the tamper-proof hold ring by heating it and possibly by clamping it with pliers. This has the drawback that placing the tamper-proof hold ring on the neck requires a heating system, and possibly a clamping system, which considerably complicates placement of the cap, and it also requires modification of conventional capping machines.
Other caps having tamper-proof hold rings are simpler to remove from a mold. But, these tamper-proof hold rings do not cooperate with a mating ring or collar of a standard container neck. Instead, these hold rings copperate with special means which are provided on the container neck.